August 8 - Groupon Inc subscribers have more than doubled to 115 million since the end of last year, according to a person familiar with the situation.

groupon.com

Groupon filed plans in June for a $750 million initial public offering that may value the company at as much as $20 billion. However, Groupon is facing more competition from big rivals including Google Inc and Facebook.

Groupon had 50.58 million subscribers at the end of 2010. That jumped 64 percent to 83.1 million at the end of the first quarter.

Since then, the number of subscribers has climbed to 115 million, the person said. That means subscribers are up about 38 percent since March 31.

Most of the recent growth has not come through acquisitions because Groupon has not bought many companies lately, the person added.

Groupon has grown rapidly since it started in late 2008. Revenue surged to $713 million last year from $30 million in 2009. In the first quarter of this year alone revenue topped $644 million.

"There are few growth opportunities on the scale of companies like Groupon," said Lou Kerner, vice president in equity research at Wedbush Securities covering social media and e-commerce. "That's really what a lot of investors are seeking today."

However, Groupon has spent a lot to lure subscribers and generate revenue growth. The company spent $208 million on marketing during the first quarter of this year, up from $4 million in the same period a year earlier.

Such spending left Groupon with a net loss attributable to common stockholders of $146 million in the first quarter of this year.

(Reporting by Alistair Barr; Editing by Phil Berlowitz, Bernard Orr)